Electrodeposition of nickel from an acid bath



Patented 7, 1948 amc'raonsrosrrron or menu. FROM Anson) ns'rn Henry Brown, Detroit, Micln, minor to The Udylite Corporation, Detroit, Mich, a corporation of Delaware No Drawing. Application May 1, 1946,

- Serial No. 666,508 1 2 Claims. (Cl. 204-49) This invention relates to the electrodeposition of bright plate from aqueous acidic nickel baths.

This object can be accomplished by the addition of soluble alpha unsaturated aliphatic nitro compounds such as p-nitro styrene sulfonic acid to acidic nickel baths such as those listed in Table II.

The alpha unsaturated aliphatic nitro compounds are more effective in giving brighter plate than the saturated aliphatic nitro compounds, when used in conjunction with a compound of Table III, or when a group is in the same molecule containing the aliphatic nitro group. This is, evidently, because of the contribution of the olefinic unsaturation to the unsaturation ofthe aliphatic nitro group itself, in a somewhat similar way as butyraldehyde compared with crotonaldehyde. The latter is much more effective in the nickel bath.

It is in general preferred to use the sulionic derivatives of the alpha unsaturated aliphatic nitro compounds because of the low solubility and oily effects of the compounds without sulionic groups. These sulfonic derivatives, such as EX- amples l and 2 (Table I) can be used alone in the acidic nickel baths to give very bright ductile plate. They can also be used with the compoundsof Table III but the enhancement is then not as marked as if the nitro compound did not contain a group.

The compounds of Table I are best used in the concentration values given, though higher concentrations up to saturation can be used, especially in cold baths.

Besides the nickel salts listed in Table II, other nickel salts such as nickel sulfamate may 2 be used in whole or in part. In fact, any acidic nickel bath may be used for the purpose of this invention which is capable of producing thick, adherent, and preferably ductile dull deposits.

The best pH values to use are 3-5, though higher or lower may be used, depending mainly on the temperature used (the higher the temperature, the lower the pH usually used). The preferred temperatures are 122-140" F. Too'low pH (below 2.0-2.5) tends to slow the rate of brightening.

The best bufler to use is boric acid, even though other buffers such as formates and citrates may be used. If the latter are used, it is preferable to also use boric acid with them.

It is bestnot to have any ammonium salts in the warm baths, or keep their concentration below about 3 g./l. oi ammonium chloride, because of the adverse eflects of excessive ammonium salts on the ductility and color of the plate from warm baths.

Table I Grams per liter (1) 2-nitrovinyl benzene sulionic (o, m, or

p) (Ni, Co. Fe, Na, K or Mg salt) (5- nitrostyrene sulfonic acids) 0.3-5

IYTO: nmsO-cnmzn (2) o-Chlor p-nltrostyrene para sulionic 0H acid (Ni, Co, Fe, Na, K, or Mg salt) 0.3-5 T 35 (3) l-nitro isobutylene .1-1

CH: NO:

40 (4) B-Nitrostyrene .05-.2 (5) Nitro ethylene .?.-.2

Table II B 11 Bath NlSOi-gHLO, NiCln/(iHsO, N15,, u at 'r el DH 513% Formula gJL Amps./sq.it.

as 10-75 1-5 10-100 1.54s 10-85 2-0 10-75 2-0 10-85 2-6 10-85 2-6 10-100 2-0 10-85 3 Table III Opt. cone. in the bath g./l. o-Benzoyl sulfimide (saccharin) 1-3 Benzene sulfonamide 1-3 Toluene sulfonamide (0 or p) 1-3 Naphthalene disulfonic acids a 1-4 Diphenyl sulfone sulfonic acid 1-4 Benzene disulfonic acid 10-15 I claim:

1. A bath for electrodepositing' bright nickel I comprising an aqueous acid solution of a material selected from the group consisting of nickel chloride, nickel sulfate, a mixture of nickel sulfate and nickel chloride, a mixture of nickel fluoborate and nickel chloride, a mixture of nickel fiuoborate and nickel sulfate, and a mixture of nickel sulfate, nickel chloride, and nickel fluoborate, said solution having dissolved therein 2- nitrovinyl benzene sulionic acid in an amount falling within a range of from about .3 gram per liter to saturation, said hath having a pH falling within a range of from 2 to 6.

2. A method for eiectrodepositing bright nickel comprising the step of electrodepositing bright -nickel from an aqueous acid solution of a. ma-

terlal selected from the group consisting oi nickel chloride, nickel sulfate, a mixture of nickel sulfate and nickel chloride, a mixture of nickel fluoborate and nickel chloride, 9. mixture of nickel fluoborate and nickel sulfate, and a mixture of nickel sulfate, nickel chloride, and nickel fluoborate, said solution having dissolved therein 2-nitrovinyl benzene suli'onic acid in an amount falling within a range of from about .3 gram per liter to saturation, said bath having a pH falling within a range of from HENRY BROWN.

REFERENCES CITED The follc wing references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,029,387 Pine Feb. 4, 1936 2,191,813 Brown Feb. 27, 1940 OTHER REFERENCES Linick, Metal Finishing (Nov. 1941), page 611.

Modern Electroplating, special volume, published by Electrochemical Society (1942), pages 242 and 243. 

